Field of Disclosure
Embodiments described herein generally relate to formulating an empirical correlation model for assessing the productivity of wells having a snaky zig-zag shape and a method for improving oil production from a well according to the empirical correlation model.
Description of the Related Art
The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Extended reach and extreme long reach horizontal wells have been deployed by oil industries with a goal to maximize the oil recovery as well as to reduce the development cost per barrel, in many upstream development projects such as deep water, deep gas, and tight reservoirs. Several methods exist to estimate well productivity by Inflow Performance Relationship (IPR) correlations. However, a critical drawback of the existing methods is that they assume the extended and long reach horizontal wells are drilled either at ninety degrees or at a certain inclined angle.
In contrast, geo-steering surveys have revealed that the oil wells have a snaky zig-zag shape. The zig-zag shape of the wells is dictated by the geographical topology of the region where the well is drilled, as well as factors such as isolated sand stringers, permeability, and porosity of the region. Furthermore, due to drilling difficulties in certain geographical regions, the well is constrained to have a zig-zag shape. Currently, the impact of having such a snaky zig-zag shape for the extended reach horizontal wells on the IPR of the well is addressed only through expensive reservoir simulation tools and numerical models. Such a technique proves to be cost-inefficient. Furthermore, simulation of the numerical models incurs an unacceptable processing time, which if constrained to be within a certain bound, may result in inaccurate assessment of the IPR of the well.
Additionally, determining the performance of snaky oil wells has proven to be challenging due to the lack of unanimity in defining the snaky well parameters. For instance, Han. G et al. describe in their work “Study on Undulating Well in Anisotropic Reservoir in Semi-Analytical Method”, SPE 167319, prepared at SPE Kuwait Oil and Gas Show, 7-10 Oct. 2013, Kuwait, and incorporated herein by reference in its entirety, that the snaky well can be characterized by an undulation amplitude parameter. R. Kamkom et al., describe in their work “Predicting Undulating Well Performance”, SPE 109761, prepared at SPE annual Technical Conference and Exhibition, 11-14 Nov. 2007, California USA, and incorporated herein by reference in its entirety, that the snaky well can be characterized by the number of cycles.
A drawback of the above stated works is that they use semi-analytical models and analytical line source models to develop the productivity performance of snaky horizontal well. Such approaches are time-inefficient and thus cannot be easily implemented as a quick look-up tool to determine the performance of snaky wells. Furthermore, in the works of Cheng. M. in “IPR for solution Gas drive Slanted/Horizontal Wells”, SPE 20720, presented at SPE Annual Technical Conference and Exhibition, 23-26 Sep. 1990, New Orleans USA, and incorporated herein by reference in its entirety, and Wiggins. M. et al., in “A Two Phase IPR for horizontal Wells”, SPE 94302, presented at 2005 SPE Production and Operation Symposium, 17-19 Apr. 2005, Oklahoma USA, and incorporated by reference herein in its entirety, the developed inflow performance models focused only on inclined horizontal wells (as opposed to snaky wells) for saturated reservoirs.
Accordingly, there is a requirement to develop an empirical correlation technique that can be used to assess the impact of the snaky zig-zag shape of the well on the well's productivity (i.e., IPR of the well). Furthermore, the empirical correlation technique serves as a quick look-up tool to assess the well's productivity in a time-feasible fashion.